// Copyright (C) 2011  Carl Rogers
// Released under MIT License
// license available in LICENSE file, or at http://www.opensource.org/licenses/mit-license.php

#include "cnpy.h"

#include <stdint.h>

#include <algorithm>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <regex>
#include <stdexcept>

char cnpy::BigEndianTest(int size)
{
  if (size == 1)
    return '|';
  int x = 1;
  return (((char*)&x)[0]) ? '<' : '>';
}

char cnpy::map_type(const std::type_info& t)
{
  if (t == typeid(float))
    return 'f';
  if (t == typeid(double))
    return 'f';
  if (t == typeid(long double))
    return 'f';

  if (t == typeid(int))
    return 'i';
  if (t == typeid(char))
    return 'i';
  if (t == typeid(signed char))
    return 'i';
  if (t == typeid(short))
    return 'i';
  if (t == typeid(long))
    return 'i';
  if (t == typeid(long long))
    return 'i';

  if (t == typeid(unsigned char))
    return 'u';
  if (t == typeid(unsigned short))
    return 'u';
  if (t == typeid(unsigned long))
    return 'u';
  if (t == typeid(unsigned long long))
    return 'u';
  if (t == typeid(unsigned int))
    return 'u';

  if (t == typeid(bool))
    return 'b';

  if (t == typeid(std::complex<float>))
    return 'c';
  if (t == typeid(std::complex<double>))
    return 'c';
  if (t == typeid(std::complex<long double>))
    return 'c';

  else
    return '?';
}

template <>
std::vector<char>& cnpy::operator+=(std::vector<char>& lhs, const std::string rhs)
{
  lhs.insert(lhs.end(), rhs.begin(), rhs.end());
  return lhs;
}

template <>
std::vector<char>& cnpy::operator+=(std::vector<char>& lhs, const char* rhs)
{
  // write in little endian
  size_t len = strlen(rhs);
  lhs.reserve(len);
  for (size_t byte = 0; byte < len; byte++) {
    lhs.push_back(rhs[byte]);
  }
  return lhs;
}

void cnpy::parse_npy_header(unsigned char* buffer, size_t& word_size, std::vector<size_t>& shape, bool& fortran_order,
                            std::string& typeName)
{
  // std::string magic_string(buffer,6);
  uint8_t     major_version = *reinterpret_cast<uint8_t*>(buffer + 6);
  uint8_t     minor_version = *reinterpret_cast<uint8_t*>(buffer + 7);
  uint16_t    header_len    = *reinterpret_cast<uint16_t*>(buffer + 8);
  std::string header(reinterpret_cast<char*>(buffer + 9), header_len);

  size_t loc1, loc2;

  // fortran order
  loc1          = header.find("fortran_order") + 16;
  fortran_order = (header.substr(loc1, 4) == "True" ? true : false);
  if (fortran_order)
    throw std::runtime_error("npy input file: 'fortran_order' must be false, use: arr2 = np.ascontiguousarray(arr1)");

  // shape
  loc1 = header.find("(");
  loc2 = header.find(")");

  std::regex  num_regex("[0-9][0-9]*");
  std::smatch sm;
  shape.clear();

  std::string str_shape = header.substr(loc1 + 1, loc2 - loc1 - 1);
  while (std::regex_search(str_shape, sm, num_regex)) {
    shape.push_back(std::stoi(sm[0].str()));
    str_shape = sm.suffix().str();
  }

  // endian, word size, data type
  // byte order code | stands for not applicable.
  // not sure when this applies except for byte array
  loc1              = header.find("descr") + 9;
  bool littleEndian = (header[loc1] == '<' || header[loc1] == '|' ? true : false);
  assert(littleEndian);

  // char type = header[loc1+1];
  // assert(type == map_type(T));

  std::string str_ws = header.substr(loc1 + 2);
  loc2               = str_ws.find("'");
  word_size          = atoi(str_ws.substr(0, loc2).c_str());
  if (header.substr(loc1 + 1, 1) == "i") {
    typeName = "int";
  } else if (header.substr(loc1 + 1, 1) == "u") {
    typeName = "uint";
  } else if (header.substr(loc1 + 1, 1) == "f") {
    typeName = "float";
  }
  typeName = typeName + std::to_string(word_size * 8);
}

void cnpy::parse_npy_header(FILE* fp, size_t& word_size, std::vector<size_t>& shape, bool& fortran_order,
                            std::string& typeName)
{
  char   buffer[256];
  size_t res = fread(buffer, sizeof(char), 11, fp);
  if (res != 11)
    throw std::runtime_error("parse_npy_header: failed fread");
  std::string header = fgets(buffer, 256, fp);
  assert(header[header.size() - 1] == '\n');

  size_t loc1, loc2;

  // fortran order
  loc1 = header.find("fortran_order");
  if (loc1 == std::string::npos)
    throw std::runtime_error("parse_npy_header: failed to find header keyword: 'fortran_order'");
  loc1 += 16;
  fortran_order = (header.substr(loc1, 4) == "True" ? true : false);
  if (fortran_order)
    throw std::runtime_error("npy input file: 'fortran_order' must be false, use: arr2 = np.ascontiguousarray(arr1)");

  // shape
  loc1 = header.find("(");
  loc2 = header.find(")");
  if (loc1 == std::string::npos || loc2 == std::string::npos)
    throw std::runtime_error("parse_npy_header: failed to find header keyword: '(' or ')'");

  std::regex  num_regex("[0-9][0-9]*");
  std::smatch sm;
  shape.clear();

  std::string str_shape = header.substr(loc1 + 1, loc2 - loc1 - 1);
  while (std::regex_search(str_shape, sm, num_regex)) {
    shape.push_back(std::stoi(sm[0].str()));
    str_shape = sm.suffix().str();
  }

  // endian, word size, data type
  // byte order code | stands for not applicable.
  // not sure when this applies except for byte array
  loc1 = header.find("descr");
  if (loc1 == std::string::npos)
    throw std::runtime_error("parse_npy_header: failed to find header keyword: 'descr'");
  loc1 += 9;
  bool littleEndian = (header[loc1] == '<' || header[loc1] == '|' ? true : false);
  assert(littleEndian);

  // char type = header[loc1+1];
  // assert(type == map_type(T));

  std::string str_ws = header.substr(loc1 + 2);
  loc2               = str_ws.find("'");
  word_size          = atoi(str_ws.substr(0, loc2).c_str());
  if (header.substr(loc1 + 1, 1) == "i") {
    typeName = "int";
  } else if (header.substr(loc1 + 1, 1) == "u") {
    typeName = "uint";
  } else if (header.substr(loc1 + 1, 1) == "f") {
    typeName = "float";
  }
  typeName = typeName + std::to_string(word_size * 8);
}

void cnpy::parse_zip_footer(FILE* fp, uint16_t& nrecs, size_t& global_header_size, size_t& global_header_offset)
{
  std::vector<char> footer(22);
  fseek(fp, -22, SEEK_END);
  size_t res = fread(&footer[0], sizeof(char), 22, fp);
  if (res != 22)
    throw std::runtime_error("parse_zip_footer: failed fread");

  uint16_t disk_no, disk_start, nrecs_on_disk, comment_len;
  disk_no              = *(uint16_t*)&footer[4];
  disk_start           = *(uint16_t*)&footer[6];
  nrecs_on_disk        = *(uint16_t*)&footer[8];
  nrecs                = *(uint16_t*)&footer[10];
  global_header_size   = *(uint32_t*)&footer[12];
  global_header_offset = *(uint32_t*)&footer[16];
  comment_len          = *(uint16_t*)&footer[20];

  assert(disk_no == 0);
  assert(disk_start == 0);
  assert(nrecs_on_disk == nrecs);
  assert(comment_len == 0);
}

cnpy::NpyArray load_the_npy_file(FILE* fp)
{
  std::vector<size_t> shape;
  size_t              word_size;
  std::string         typeName;
  bool                fortran_order;
  cnpy::parse_npy_header(fp, word_size, shape, fortran_order, typeName);

  cnpy::NpyArray arr(shape, word_size, fortran_order, typeName);
  size_t         nread = fread(arr.data<char>(), 1, arr.num_bytes(), fp);
  if (nread != arr.num_bytes())
    throw std::runtime_error("load_the_npy_file: failed fread");
  return arr;
}

cnpy::NpyArray load_the_npz_array(FILE* fp, uint32_t compr_bytes, uint32_t uncompr_bytes)
{
  std::vector<unsigned char> buffer_compr(compr_bytes);
  std::vector<unsigned char> buffer_uncompr(uncompr_bytes);
  size_t                     nread = fread(&buffer_compr[0], 1, compr_bytes, fp);
  if (nread != compr_bytes)
    throw std::runtime_error("load_the_npy_file: failed fread");

  int      err;
  z_stream d_stream;

  d_stream.zalloc   = Z_NULL;
  d_stream.zfree    = Z_NULL;
  d_stream.opaque   = Z_NULL;
  d_stream.avail_in = 0;
  d_stream.next_in  = Z_NULL;
  err               = inflateInit2(&d_stream, -MAX_WBITS);

  d_stream.avail_in  = compr_bytes;
  d_stream.next_in   = &buffer_compr[0];
  d_stream.avail_out = uncompr_bytes;
  d_stream.next_out  = &buffer_uncompr[0];

  err = inflate(&d_stream, Z_FINISH);
  err = inflateEnd(&d_stream);

  std::vector<size_t> shape;
  size_t              word_size;
  bool                fortran_order;
  std::string         typeName;
  cnpy::parse_npy_header(&buffer_uncompr[0], word_size, shape, fortran_order, typeName);

  cnpy::NpyArray array(shape, word_size, fortran_order, typeName);

  size_t offset = uncompr_bytes - array.num_bytes();
  memcpy(array.data<unsigned char>(), &buffer_uncompr[0] + offset, array.num_bytes());

  return array;
}

cnpy::npz_t cnpy::npz_load(std::string fname)
{
  FILE* fp = fopen(fname.c_str(), "rb");

  if (!fp) {
    throw std::runtime_error("npz_load: Error! Unable to open file " + fname + "!");
  }

  cnpy::npz_t arrays;

  while (1) {
    std::vector<char> local_header(30);
    size_t            headerres = fread(&local_header[0], sizeof(char), 30, fp);
    if (headerres != 30)
      throw std::runtime_error("npz_load: failed fread");

    // if we've reached the global header, stop reading
    if (local_header[2] != 0x03 || local_header[3] != 0x04)
      break;

    // read in the variable name
    uint16_t    name_len = *(uint16_t*)&local_header[26];
    std::string varname(name_len, ' ');
    size_t      vname_res = fread(&varname[0], sizeof(char), name_len, fp);
    if (vname_res != name_len)
      throw std::runtime_error("npz_load: failed fread");

    // erase the lagging .npy
    varname.erase(varname.end() - 4, varname.end());

    // read in the extra field
    uint16_t extra_field_len = *(uint16_t*)&local_header[28];
    if (extra_field_len > 0) {
      std::vector<char> buff(extra_field_len);
      size_t            efield_res = fread(&buff[0], sizeof(char), extra_field_len, fp);
      if (efield_res != extra_field_len)
        throw std::runtime_error("npz_load: failed fread");
    }

    uint16_t compr_method  = *reinterpret_cast<uint16_t*>(&local_header[0] + 8);
    uint32_t compr_bytes   = *reinterpret_cast<uint32_t*>(&local_header[0] + 18);
    uint32_t uncompr_bytes = *reinterpret_cast<uint32_t*>(&local_header[0] + 22);

    if (compr_method == 0) {
      arrays[varname] = load_the_npy_file(fp);
    } else {
      arrays[varname] = load_the_npz_array(fp, compr_bytes, uncompr_bytes);
    }
  }

  fclose(fp);
  return arrays;
}

cnpy::NpyArray cnpy::npz_load(std::string fname, std::string varname)
{
  FILE* fp = fopen(fname.c_str(), "rb");

  if (!fp)
    throw std::runtime_error("npz_load: Unable to open file " + fname);

  while (1) {
    std::vector<char> local_header(30);
    size_t            header_res = fread(&local_header[0], sizeof(char), 30, fp);
    if (header_res != 30)
      throw std::runtime_error("npz_load: failed fread");

    // if we've reached the global header, stop reading
    if (local_header[2] != 0x03 || local_header[3] != 0x04)
      break;

    // read in the variable name
    uint16_t    name_len = *(uint16_t*)&local_header[26];
    std::string vname(name_len, ' ');
    size_t      vname_res = fread(&vname[0], sizeof(char), name_len, fp);
    if (vname_res != name_len)
      throw std::runtime_error("npz_load: failed fread");
    vname.erase(vname.end() - 4, vname.end()); // erase the lagging .npy

    // read in the extra field
    uint16_t extra_field_len = *(uint16_t*)&local_header[28];
    fseek(fp, extra_field_len, SEEK_CUR); // skip past the extra field

    uint16_t compr_method  = *reinterpret_cast<uint16_t*>(&local_header[0] + 8);
    uint32_t compr_bytes   = *reinterpret_cast<uint32_t*>(&local_header[0] + 18);
    uint32_t uncompr_bytes = *reinterpret_cast<uint32_t*>(&local_header[0] + 22);

    if (vname == varname) {
      NpyArray array = (compr_method == 0) ? load_the_npy_file(fp) : load_the_npz_array(fp, compr_bytes, uncompr_bytes);
      fclose(fp);
      return array;
    } else {
      // skip past the data
      uint32_t size = *(uint32_t*)&local_header[22];
      fseek(fp, size, SEEK_CUR);
    }
  }

  fclose(fp);

  // if we get here, we haven't found the variable in the file
  throw std::runtime_error("npz_load: Variable name " + varname + " not found in " + fname);
}

cnpy::NpyArray cnpy::npy_load(std::string fname)
{
  FILE* fp = fopen(fname.c_str(), "rb");

  if (!fp)
    throw std::runtime_error("npy_load: Unable to open file " + fname);

  NpyArray arr = load_the_npy_file(fp);

  fclose(fp);
  return arr;
}
